| Message ID | 2535-1695168070.831792@Ze3y.dhYT.s3fx (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
| Series | [v1] iio: pressure: ms5611: ms5611_prom_is_valid false negative bug | expand |
On Wed, 20 Sep 2023 10:01:10 +1000 Alexander Zangerl <az@breathe-safe.com> wrote: > the ms5611 driver falsely rejects lots of MS5607-02BA03-50 chips > with "PROM integrity check failed" because it doesn't accept a prom crc > value of zero as legitimate. > > according to the datasheet for this chip (and the manufacturer's > application note about the prom crc), none of the possible > values for the crc are excluded - but the current code > in ms5611_prom_is_valid() ends with > > return crc_orig != 0x0000 && crc == crc_orig > > i've discussed this with the original author of the driver (tomasz > duszynski) and he indicated that at that time (2015) he was dealing with > some faulty chip samples which returned blank data under some > circumstances and/or followed example code which indicated crc zero > being bad (i can't find any traces of any such online, however). > > as far as i can tell this exception should not be applied anymore; we've > got a few hundred custom boards here with this chip where large numbers > of the prom have a legitimate crc value 0, and do work fine, but which the > current driver code wrongly rejects. > > Signed-off-by: Alexander Zangerl <az@breathe-safe.com> > Fixes: c0644160a8b5 ("iio: pressure: add support for MS5611 pressure and temperature sensor") Applied with some tweaks to the patch description to shorten it a little whilst keeping all the information. Also marked for stable inclusion. Applied to the fixes-togreg branch of iio.git Thanks, Jonathan > --- > drivers/iio/pressure/ms5611_core.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/iio/pressure/ms5611_core.c b/drivers/iio/pressure/ms5611_core.c > index 5c7a734ede54..9980c6f3335e 100644 > --- a/drivers/iio/pressure/ms5611_core.c > +++ b/drivers/iio/pressure/ms5611_core.c > @@ -79,7 +79,7 @@ static bool ms5611_prom_is_valid(u16 *prom, size_t len) > > crc = (crc >> 12) & 0x000F; > > - return crc_orig != 0x0000 && crc == crc_orig; > + return crc == crc_orig; > } > > static int ms5611_read_prom(struct iio_dev *indio_dev)
diff --git a/drivers/iio/pressure/ms5611_core.c b/drivers/iio/pressure/ms5611_core.c index 5c7a734ede54..9980c6f3335e 100644 --- a/drivers/iio/pressure/ms5611_core.c +++ b/drivers/iio/pressure/ms5611_core.c @@ -79,7 +79,7 @@ static bool ms5611_prom_is_valid(u16 *prom, size_t len) crc = (crc >> 12) & 0x000F; - return crc_orig != 0x0000 && crc == crc_orig; + return crc == crc_orig; } static int ms5611_read_prom(struct iio_dev *indio_dev)
the ms5611 driver falsely rejects lots of MS5607-02BA03-50 chips with "PROM integrity check failed" because it doesn't accept a prom crc value of zero as legitimate. according to the datasheet for this chip (and the manufacturer's application note about the prom crc), none of the possible values for the crc are excluded - but the current code in ms5611_prom_is_valid() ends with return crc_orig != 0x0000 && crc == crc_orig i've discussed this with the original author of the driver (tomasz duszynski) and he indicated that at that time (2015) he was dealing with some faulty chip samples which returned blank data under some circumstances and/or followed example code which indicated crc zero being bad (i can't find any traces of any such online, however). as far as i can tell this exception should not be applied anymore; we've got a few hundred custom boards here with this chip where large numbers of the prom have a legitimate crc value 0, and do work fine, but which the current driver code wrongly rejects. Signed-off-by: Alexander Zangerl <az@breathe-safe.com> Fixes: c0644160a8b5 ("iio: pressure: add support for MS5611 pressure and temperature sensor") --- drivers/iio/pressure/ms5611_core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)